1. Field of the Invention
The present invention relates to methods for producing resin films or layered articles which exhibit excellent gas barrier properties under high humidity conditions.
2. Description of the Related Art
Films made of polyvinyl alcohol are known to have good gas barrier properties and are used widely in wrapping material applications and the like. Unfortunately, the gas barrier properties of such films of polyvinyl alcohol depend on humidity so greatly that gas barrier properties of such films will deteriorate under high humidity conditions. As a solution of such a problem, U.S. Pat. No. 5,552,479 discloses a method for producing a gas barrier film by heat treating, under specific conditions, a film formed from a mixture of polyvinyl alcohol and poly(meth)acrylic acid.
Films produced by the above-mentioned method have somewhat improved gas barrier properties under high humidity conditions in comparison to films before heat treatment, but their performances are not satisfactory yet.